Piston ring



V. J. SWANSON ET! AL July 14, 1936.

PISTON RING Fil ed March 19, 1954 Patented July 14, 1936 PATENT OFFl-GE am PISTON RING :Yerner J. Swanson,

Ya ns, iihicagq, 111.: said Swanson mliu i t an Ja e ..said Yar as i to 7 Application Marsh 19, 1 934, s rial-No. 716,230

6 cla ms. (-01- .3Q -2.

This invention relates to piston rings adapted for conventional use in gasoline and oil internal combustion automobile motors and the like-but overcomes the disadvantages-of the types of piston rings now in-use.

The rings heretofore-used have failed to provide proper oil and pressure seals, they have worn-out too rapidly, they have caused damage to c'ylinder walls thr ll h sticking, "breaking and "melting, they have failed to conduct away the heat from the piston head, and in general they have not been entirely satisfactory.

This invention therefore has among its I objects:

The provision of a piston ring which is -commerciall-y practicable to manufacture, use and sell. l

{The provision of a piston ring isreadily installed and is applicable to existing piston designs. r

'The provision of I a :piston ring -which will efii- -ciently "seal compression in a cylinder.

Theprovision of a 'piston'ring which-will control "the amount of oil reajching the combustion chamber of -a cylinder.

The provision of a piston ring which will not *become-inefiicient because 'of-rock-i-nig of the piston.

' Thefprovision :of a-piston-ring =-w-hiohwill-properlyallow and compensate fpr expansion and contraction of piston and cylinder walls.

' The provision "of apiston --ring"-whieh wlll pre- "vent dilution of --the;-motor oil "by gasoline =from "thecombustionchamber.

The provision of a-piston ringwhlch'willneed little or no breaking in -orrunning-inbut which will'have alonglife. 7

"The provision of a piston'ring-which wilkprevent carbonization of the oil 'filmon the-cylinder wall.

ring 'flutter and similar troubles.

The provision of apiston-ring-which will-uot :cause the -ppiston to be weakened.

The provision of apiston-ring which willaexert auniform radial pressure at all times, will --not stick inthe groove, will be self-centering in-the groove, will be flexible enough 'to follow :slight va-riations=in-the eylinder--wall, will not depend 'itain clearance -'for the skirt, -vv'i'll keep frict'ion at 'a minimum, will not affect the operation or not dependon -a particular g-rade of oi1,'- will-' not depend on springs-or the-like, will allow eoncen- --tration of rings at the head-of the piston-and form asicommonlyseen at V space-=14 :for the circulation --for its operation upon the-allowance of -a 'cer- V :groove I Landrings 18 construction of other {parts of *the engine,*-will -.will avoid the building up of cylinder pressures abehinel the ring, and .will provide a flat surface in .contact with the cylinder wall.

(Either objects and functions, including the provision ofiaunique structure .for a piston ring. .will appear.

The principal objections to the present types .of .piston rings are that inorderjto seal .thetpressure and the .oil the tension has to be unduly :increased, must the runa long time to be broken in and seated properly, at which time .=they.are 'Lu'sually worn out. .lItldid ,not conduct :away the aheat -3f-I'Om;th6 piston head, .it either .fragile :or else too stifi to, allow ready installation. In :many other .ways all; was not satisfactory and its presentis onlyiacoml'promise, an attempt to .remedy .an ill without cu-ring it.

The present invention .overcomes the tdiflicul- I itiesbythe useof:hydraulicipressure, broad bear- 20 .ing surfaces, line contacts with the piston, lthe iuseof roundedorbeveled inner .corners, and .an I :entirelymewdesignand principle-of construction and operation.

The preferred embodiment of the invention is =inore-fullyexplained with reference to :the single .drawing hereby .made

a part .of .this specification. :In the'drawing:

:Eigure 1 shows a partial cross sectiontof acyl- .indenheadand aipiston head usinglthetpreferred embodimenttof the invention;

: Figure i2 is anlenlargedyiew of .a .vportiontof :the samei'section showing one of theisetsofrings ":slmilar parts in the drawing and-in the descrip- I'he-provision of'a piston-rinewhieh will-avoid in pos itlon in:acylinden-with-the side-H of-the piston in a relation .of normal clearance-with the surfaced-3 of the cylinder wallli. This clearance is-exaggerated in the drawingfor-purposes of-clearness. -n=the outside of the-eylinder-wallis-theusual of water -and;the

eustomary jacket' lfi around this-water space.

whe-piston rings l6 and |6a are in place in-ring and l 8a in groove 19.

:1he number of pairs :of rings may -be varied without departing from the spirit of the invention. 'iBelow;-the=seeond pair airings-in thispreferred embodiment of the invention, there is an aperture 20 in the piston wall to allow for the ready escape of surplus oil.

The rings 16 and Mia, and I8 and l8a, are used in pairs, each member of which is complemental to the other. The enlargement in Figure 2 shows them clearly as to shape and relationship. The outer surface 2| of each ring is machined to be accurately cylindrical and is usually honed to a mirror-like finish. This cylindrical surface terminates in a sharp corner where it is intersected by the plane surface 22 on each ring. This plane surface is at right angles to the axis of the ring. The plane surface merges into the rounded corner 23 which in turn merges into an inner cylindrical surface 24 parallel to the cylindrical surface 2|. This cylindrical surface is intersected to form a second sharp corner by the plane surface 25, which is at right angles to the axis of the ring and parallel to the plane of the surface 22. The other boundary of plane surface 25 is a coneshaped surface 26, indicated lying diagonally in the sections shown. Such surface leads into a third plane surface 21, parallel to the others, which forms a second sharp and right angled corner with the outer cylindrical surface 2|.

The two rings of the pair are identical. It is apparent that they may be used in conjunction, with the plane faces 25 in contact or separated as circumstances require.

The groove H in which the rings are used is cut into the wall of the piston. Its depth is greater than the thickness of the ring from face 2| to face 24 and its vertical dimension at the face of the piston as indicated is greater than the corresponding dimension of the two rings used in it. The amount by which the vertical dimension is greater than the corresponding dimension of the two rings may be varied to suit conditions, but for average use it has been found that this dimension should equal slightly more than the corresponding dimension of the two rings together.

The inner face 28 of the groove is cylindrical except where it merges into the rounded corners 29. The conformation of these corners is critical. They must be cut on a curve and merged into the adjoining surfaces in such a way that the contact between the wall of the groove and the surface of the ring is only at a comparatively narrow line around the ring and groove. The outer part 30 of the groove is cut to a conical shape which is intersected at an angle by a hypothetical continuation of the plane surface 22.

This angle may be varied to suit circumstances but it has been found best to make it thirty degrees from a perpendicular to a plane tangential to the cylindrical surface The radii of the curves 23 and 29 may be varied within limits, as may be the location of their centers, provided that the shapes be such that the narrow line of contact is maintained and the groove is wider at its mouth than at its inner parts.

It has been found that when the ring is considered as in contact with one or the other side of the groove the centers 23a and 29a. may be on a line a little less than half the distance from the outer edge of the ring to the center of the groove, the center 23a for the radius 231) of curve 23 may be at the position of the surface of the adjacent cylinder wall l3 and the center 29a for curve 29 separated therefrom by about one fourth of the distance from such wall to the bottom 28 of the groove.

- The radius 2317 may be slightly greater than radius 291), the two being, for instance in the ratio of I25 and H5. These dimensions as well as the others found best in the particular case, and the placement of the various centers and the like, are shown in Figure 2. These may all be varied in amount and in respective proportions to suit the particular case and are shown merely as an illustration and as a guide to proportioning and placement.

When the rings are placed in the groove on the piston they are free and have some room for movement. When they are together the two faces 25 are in contact. When displaced towards one side of the groove contact and seal is made with that side. When displaced toward the other side the contact and seal is there. The two rings may be separated within the groove, leaving a space between faces 25, which is the operating position of the rings.

At all times there is an open space between faces 26 and 21 and a space between the inner face 28 of the groove and the faces 24. The outer face 2| of the ring is in uniform and sealing contact with the cylinder wall I3, and the corners bounding such contacting ring face are sharp and at ninety degree angles.

A diagonal opening cut 3| shown in Figure 3 is provided in each ring to allow it to be expanded or contracted. This slot need not be diagonal as shown but may be vertical or of any desired shape.

As shown by the drawing the rings are comparatively wide and shallow, whereas most other rings are narrow and deep. The proportioning of these new rings, as compared to old ones, allows great flexibility, easier application, less breakage, and less friction.

In installing these new rings, it is wise to flood both the rings and the grooves with oil before inserting the piston into the cylinder. A large part of this oil will be trapped behind the ring to form a cushion, the effect which is of great importance. After the engine is in operation the normal supply of oil in the cylinder will keep the cushion replenished.

The operation of follows:

On the intake stroke the piston moves down. The inertia of the rings and their drag against the cylinder walls causes them to move to the top of the grooves. This seals the explosion chamber with a line seal which promotes eflicient suction. At the same time the lower sharp corner of the lower ring scrapes oil from the cylinder wall and causes it to flow into the space behind the rings in the cylinder is as the rings, and the lower sharp edge of the top ring in the same way fills with oil the open space between the rings.

On the compression stroke the piston is moving upward and the inertia and drag of the rings cause them to move relatively downward in the groove, the lower one forming a sealing line contact between its own rounded surface and the inclined surface of the groove. The fact that the space behind the rings is already filled with oil prevents any of the gas in the explosion chamber from escaping into that space.

To this oil is added what is scraped from the surface of the cylinder by the upper edge of the ring. The space between the two rings is again kept filled in the same way. The pressure of the gases in the explosion chamber acts upon the oil in the'space behind the rings, creating a hydraulic pressure there which forces the rings into close contact with the cylinder wall. To this hydraulic pressure is added the effect of the outlower ring;

Alclose seal with the cylinder wall is there fore produced and since the lower ring is flexible and the pressure of the oil as well as of the slanted surfaces is uniform throughout, the pressure of the lower ring upon the cylinder wall is uniform all around, and there are no open spaces between the ring and the cylinder wall. Only a very thin film of oil is allowed to remain at any place on the cylinder wall. This film of oil is'never entirely removed by the rings, but

rather is constantly replenished by the oil in the openings between and around them while the rings themselves restrict it to an ideal minimum thickness.

When the motor is in operation, just before the charge in a cylinder is ignited the top ring leaves its contact with the lower ring and makes contact with the inclined wall of the groove. Therefore the two rings are spaced apart and are kept so by the building up of oil pressure because the conical space between them collects oil from the cylinder wall. The rings are now in their normal operating position, i. e., each of the rings makes contact between its rounded side and the inclined side of the groove nearest this rounded side, and the surfaces 25 are therefore spaced apart so that the oil can travel to the back of the ring. The rings do not leave their contact with the groove sides as the pressure in the oil cushion keeps them tight up against the groove side. These rings do not bounce back and forth in the groove.

The explosion pressure cannot force the top ring away from contacting with the groove sides as the pressure in the oil cushion overcomes the gaseous pressure.

At the end of the explosion stroke the rings are still spaced apart and so remain through the exhaust stroke.

Thus this new piston ring is in effect cushioned on oil and held by surfaces shaped so that they cannot bind or stick and so that a positive seal is formed in whichever direction the piston is moving. The rounded surfaces of the groove and rings allow movement of the line of contact and seal. The ring is not held immovably in a single position and at a single angle as are ordinary rings, but is properly spoken of as floating because it is able to adapt itself to minor Variations in the relative angle of the piston wall. Thus rocking of the piston will not cause the outer surface of the ring to become rounded as that surface is held flat against the cylinder wall, rather than at an angle thereto. For that reason the edges of the bearing surface of the ring remain always sharp right angles and the efiiciency of the ring in controlling the amount of oil on the cylinder wall of the explosion chamber is always retained.

Thefilm of oil left on the cylinder wall by the rings is always at the extreme of thinness, and while always present is so thin that there is no retardation of heat transmission. The oil on the wall in the explosion chamber is therefore not carbonized by the heat because that heat is trans.- mitted through it and into the wall and the water jacket and so dissipated.

The same thinness of oil allows heat to be readily transmitted from the piston rings to the cylinder wall. In addition, the wide face of the rings provides a heat transmission area practically as great as the area of the head of the piston urements and angles and so that not only is transmission away from the piston facilitated but sufiicient means of transmissionisavailable. The rings are near the head of the piston, the most efiicient place for cooling the piston, and since the piston is cooled principal-" -ly by transmission of the heat through the rings an efiicient operating piston temperature is made 1 possible.

of many rings or like expedients, but the result has been increased friction and loss of power or some similar drawback so that earlier proposed solutions were but compromises.

The fact that piston rocking is of no particular disadvantage with these with the necessity for long and very closely ma.- chined skirts on the pistons, thus allowing a saving in weight and cost.

It must be understood that conditions in an operating engine are not the same as those in a dismantled one and to the usual factors of measthe like in the static machine must be added the factors of velocity and inertia and acceleration and friction.

advantage of them to secure efiicient operation. It must also be understood that variations in shape, size and position of the members herein described may be made without departing from the spirit of the invention.

What is claimed as new and is desired to be secured by Letters Patent of the United States is:

1. In an internal combustion engine the combination of a piston having in the cylindrical wall thereof an annular groove with rounded inner new rings does away invention is based upon those factors and takes corners and diverging upper and lower walls, said V groove being of greater width than depth, and two complemental and identical split piston rings of less thickness than the depth of said groove and of less total width than the width of said groove, said rings each having one face of a plane surface with the adjacent corner rounded, the opposite face of said rings comprising a second plane opposite said rounded corner, a third plane opposite said first between said second and third planes, the inner and outer surfaces of said rings being cylindrical, said rounded corner being shaped to meet the inclined side of said groove on a line, said second plane faces being approximated and said third plane faces and said conical faces being spaced apart when said rings are positioned in said groove.

2. The combination of a piston having in the sides, and resilient complementary upper and lower piston rings of less width than and positioned in said groove, the upper ring having a rounded upper inner corner, and the lower ring having a rounded lower inner corner, said rounded portions of both rings being of less radius of curvature than said diverging sides, whereby said rings may move in said groove to make line contact with said sides, and each ring having a cylindrical outer face for fiat contact with the Wall of a cylinder.

3. The combination of a piston having in the cylindrical wall thereof a groove with rounded inner corners and diverging sides, and two resilient plane, and a conical surface radius of curvature than said diverging sides, whereby said rings may move in said groove to make line contact with said sides, and each ring having a cylindrical outer face for flat contact with the wall of a cylinder.

4. In an internal combustion engine the combination of a piston having in the cylindrical wall thereof an annular groove and diverging upper and lower walls, and complemental piston rings of less thickness than the depth of said groove, said rings each having one face of a plane surface with the adjacent corner rounded, the opposite face of said rings comprising a second plane opposite said rounded corner, a third plane opposite said first plane, and a conical surface between said second and third planes, the inner and outer sur faces of said rings being cylindrical, said rounded corner being shaped to meet the diverging wall of said groove on a line, said second plane faces being approximated and said third plane faces and said conical faces being spaced apart when said rings are positioned in said groove.

5. In an internal combustion engine the combination of a piston having in its cylindrical wall an annular groove possessing diverging sides, and

resilient coinplemental upper and lower piston rings in said groove, the upper ring having a rounded upper inner corner, and the lower ring having a rounded lower inner corner, said two rings being less wide than the mouth of said groove and wider than the bottom of said groove, the rounded corners of said rounded portions of both rings being of less radius of curvature than said diverging sides, whereby said rings may move in said groove on lines of contact with said sides, and each ring having a cylindrical outer face for flat contact with the walls of a cylinder.

6. In an internal combustion engine, the combination of a piston having in its cylindrical wall an annular groove possessing divergent sides, and complemental upper and lower piston rings in said groove, the upper ring having a rounded upper inner edge and a cut back lower outer edge, and the lower ring having a rounded lower inner edge and a cut back upper outer edge, the rounded 20 edges of said rings meeting the sides of said groove on lines of contact, and said out back edges being spaced apart. 

